bcachefs: Fix validate_bset() repair path

When we truncate a bset (due to it extending past the end of the btree
node), we can't skip the rest of the validation for e.g. the packed
format (if it's the first bset in the node).

Reported-by: syzbot+4d722d3c539d77c7bc82@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Author: Kent Overstreet

fs/bcachefs/btree_io.c

@@ -733,11 +733,8 @@ static int validate_bset(struct bch_fs *c, struct bch_dev *ca,
 			 c, ca, b, i, NULL,
 			 bset_past_end_of_btree_node,
 			 "bset past end of btree node (offset %u len %u but written %zu)",
-			 offset, sectors, ptr_written ?: btree_sectors(c))) {
+			 offset, sectors, ptr_written ?: btree_sectors(c)))
 		i->u64s = 0;
-		ret = 0;
-		goto out;
-	}
 
 	btree_err_on(offset && !i->u64s,
 		     -BCH_ERR_btree_node_read_err_fixable,
@@ -829,7 +826,6 @@ static int validate_bset(struct bch_fs *c, struct bch_dev *ca,
 			       BSET_BIG_ENDIAN(i), write,
 			       &bn->format);
 	}
-out:
 fsck_err:
 	printbuf_exit(&buf2);
 	printbuf_exit(&buf1);